1. Field of the Invention
The invention relates to memory control, and more particularly to a data processing method and system capable of reducing required memory.
2. Description of the Related Art
Orthogonal frequency division multiplexing (OFDM) uses multiple carriers to transmit data. The transmitted data is separated into multiple sub-carriers for parallel transmission, rather than being carried by only one carrier. Only a small amount of the data is transported on each sub-carrier, thus lowering the bit rate per sub-carrier. OFDM can be seen as a parallel data transmission and frequency division multiplexing technique (FDM). OFDM is a more robust against frequency selective fading and multi-path immunity.
OFDM is used for Terrestrial Digital TV broadcasting in Europe, Japan and Taiwan. In addition. OFDM is used in high-speed telephone line communications such as ADSL, and wireless LAN such as IEEE802.11a/g. Although OFDM has many advantages, it suffers from the serious defect of high Peak-to-average power ratio (PAPR). OFDM has peak higher than the average signal level because OFDM is comprised of thousands of orthogonal waves. The high peak defect results in serious problems such as nonlinear distortion and increased bit error rate (BER) at the receiver, next-channel Interference, and similar. A high-level transmitter, a high-resolution A/D and D/A converter, for example, is thus required to overcome these defects, increasing costs. Thus, discrete cosine transform (DCT) is applied to reduce PAPR, for reducing capital outlay required by OFDM.
Current PAPR reduction methods utilizing a windowing operation may require excessive storage for input data, time domain data, frequency domain data, and filtered data respectively, requiring more hardware cost. Thus, a data processing method and system capable of reducing required memory is desirable.